The Clinical Core is designed to provide cost effective support for the clinical studies in all projects. Research nursing and technical support for the recruitment of subjects, for the maintenance of shared equipment, for the scheduling of shared Human Physiology laboratories, and for preparation for and performance of individual studies will be more efficiently provided by the Core than would be possible for the individual projects. Investigators with expertise in clinical studies, norepinephrine, biochemistry, and systemic and local norepinephrine spill over will provide for maintenance of complex equipment, backup for individual study performance, and a shared resource for data analysis and handling, enhancing the ability of all projects to successfully complete these studies. Tritiated norepinephrine, a costly supply item with a defined half-life, will be purchased and prepared in bulk for cost saving. Finally, the involvement of investigators from several projects in Clinical Core activities will increase communication between projects, adding to the integrative nature of this Program Project.